PRIOR ART
Can and bottle vending machines are an important part of the soft drink industry. They are found in virtually every location where people are likely to purchase a can or bottle of soft drink at any time of day or night, where there is some form of public access and generally where there is no other convenient means for purchasing a soft drink. Thus, by way of example, one may find such dispensing machines on most or all floors of every major hotel, in places of recreational activities such as bowling alleys and movie theaters, in places of employment and in high traffic, publicly accessible locations such as airports, train stations, bus stations and the like. Historically, such vending machines have been electromechanical devices which use relays, controlling single turn motors, all interconnected by hard wired logic to dispense a single can or bottle upon acceptance of a set amount in currency.
The general idea in any vending machine control system is to simplify as much as possible the wiring harnessing and the controller in order to minimize the manufacturing and assembly costs. At the same time, the simplification should not come at the expense of versatility and reliability.
All the vending machines to which the present invention is related, are capable of vending multiple products out of columns, trays or other queuing means, where products of the same kind can be dispensed one at a time. In addition, each of these queues, or pair of queues, is activated by a separate motor or solenoid. They also have means of detecting the depletion of product (Sold-Out condition) on each queue, and means of detecting when each vending cycle is completed.
In older, non-electronic, vending machines, the Sold-Out sensor is a switch mechanically coupled to the product queue such that when the number of items in the queue drops below a certain number, the switch changes states and removes power from the corresponding motor, while at the same time turning on a Sold-Out light indicator for the particular queue. To sense the completion of the vending cycle (the HOME position), a switch coupled to a notched cam that rides on the shaft of the vending mechanism, changes states when the cycle is completed and removes power from the motor.
With the advent of microprocessors and microcontrollers, vending machine manufacturers have recently begun providing far more sophisticated vending machines which are capable of providing multiprice options to the purchaser.
In newer, electronically controlled vending machines the controller controls each motor and all switches are used as sensor only, informing the controller of Product selection,"Sold-Out" and vend completion. A basic wiring schematic for a 10-selection vending machine with 10 queues, requires:
10 Power Drivers for the Motors PA1 10 Digital Inputs to Sense Sold-Out PA1 10 Digital Inputs to Sense Home PA1 1 11-wire Motor Cable PA1 1 11-wire Sold-Out Cable PA1 1 11-wire Home Position Sensing Cable PA1 b) Motors are driven in a Matrix and all Sold-Out switches are connected in series with motors; PA1 c) The HOME switches are connected in series such that only a momentary interruption in the continuity between the first and last switch is sensed when the switch changes states. This is sufficient to signal the controller that home position is reached. The controller "knows" which motor is running and therefore it can turn it off. Normally a SPDT (Single Pole Double Throw) switch is used for the HOME position sensing. By jumpering the NO (normally open) and NC (normally closed) contacts, the continuity is interrupted only during the switching transition. The continuity does not depend on the switch actuator rest position (the so-called Closed or Open positions). Thus even if one or more motors are stuck in a non-home position, the switch circuit continuity is not broken. PA1 b) If current is flowing and the Home switch does not produce a signal within a given time period, the controller "knows" that there is a motor jam. If the current exceeds a preset maximum, the controller shuts off the motor to prevent damage to the queue. PA1 c) If no current is flowing into the motor, the controller "knows" that the selection is sold-out and the motor drive is adjusted to dispense product correctly after the queue is reloaded. PA1 b) On the MIB, one jumper each on the High Drive Select and Low Drive Select headers determines the pair of lines that drive the motor. For the Home Switch loop, jumpers and headers are provided on the MIB. A jumper block on the First Motor header of the MIB of Motor 1, jumpers from each board to the adjacent board and a jumper block on the Last Motor header of the last MIB, create the loop. PA1 c) Since DC motors do not stop abruptly when power is removed--unless there is a short across the motor--a motor brake circuit is provided on each MIB to prevent possible double product dispensing since each queue may have two or three products, each dispensed upon a partial rotation of a cam having multiple notches.